EP2882332A1

EP2882332A1 - Method and device for screening a state of ophthalmic fatigue of an individual

Info

Publication number: EP2882332A1
Application number: EP13758917.2A
Authority: EP
Inventors: Björn Drobe
Original assignee: Essilor International Compagnie Generale dOptique SA
Current assignee: EssilorLuxottica SA
Priority date: 2012-08-09
Filing date: 2013-07-25
Publication date: 2015-06-17
Anticipated expiration: 2033-07-25
Also published as: EP2882332B1; US9675242B2; FR2994378B1; WO2014023889A1; FR2994378A1; CN104519784A; US20150164315A1; BR112015001906A2; CN104519784B

Abstract

The invention relates to a method of screening a state of ophthalmic fatigue of an individual, comprising steps: a1 ) of positioning a target (120) in relation to the individual in such a way that the target is visible by at least one of the two eyes of the individual, a2) of assessment by the individual of the sharpness of the target, and a3) of deducing a state of ophthalmic fatigue of the individual depending on whether the target is seen by the individual in a sharp or blurred manner. According to the invention, prior to step a2), there is provision for a step a0) of adjusting the size of the target and/or the position of the target in relation to the individual, as a function of the age of the individual.

Description

METHOD AND DEVICE FOR DETECTING OPHTHALMIC FATIGUE STATUS OF A

INDIVIDUAL

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates generally to diagnostic methods for the ophthalmic accommodation of individuals.

It relates more particularly to a method for detecting a state of ophthalmic fatigue of an individual, comprising steps:

a1) positioning a target relative to the individual such that the target is visible by at least one of the two eyes of the individual,

a2) the individual's assessment of the sharpness of the target, and

a3) of deducing a state of ophthalmic fatigue of the individual according to whether the target is seen by the individual clearly or fuzzy.

It also relates to a device for detecting a state of ophthalmic fatigue of an individual, comprising:

a support comprising a support part to be applied against the face of an individual and a slide,

a target slidably mounted on the slide of the support, and

- At least one graduation along the slide to locate the position of the target on the slide.

BACKGROUND

Accommodation is defined as the automatic and involuntary action of the ciliary muscles to deform the eye so that it can clearly see objects at various distances.

More specifically, during accommodation, the curvature of the lens changes under the influence of the ciliary muscles, which allows the formation of clear images on the retina. The crystalline lens flattens for a clear vision of distant objects and rounds out to see the objects close together.

The minimum distance of accommodation of a given individual is then defined as the distance from which this individual can see an object in a perfectly clear manner. Below this minimum distance of accommodation, the ciliary muscles do not allow to round sufficiently the lens to allow the formation of clear images on the retina.

It is known that this minimum distance of accommodation increases with age, and that it increases more or less rapidly from one individual to another. It also increases when the individual is tired.

It is then known to measure this minimum distance of accommodation using an ophthalmic rule, better known by the English expression "RAF rule" (for "Royal Air Force rule").

This ophthalmic rule comprises, on the one hand, a metal rod graduated in diopters and meters, one end of which forms a fork to be applied against the wearer's face, and, on the other hand, a target mounted to move in translation on the stem. metallic.

The method of using this rule is to position the target on the rod opposite the fork, then to apply this fork on the face of the individual by maintaining the metal rod in the axis of the eyes of the individual, and finally to gradually bring the target to a limit position at which the individual does not see this target clearly.

The minimum distance of accommodation can then be read directly on the graduation provided for this purpose.

However, the Applicant has found that the use of this ophthalmic rule generally results in overestimated measures, in that the measured minimum accommodation distances are generally lower than the actual minimum accommodation distances of the carriers.

Prescription errors ensue, in the sense that no pair of glasses is prescribed to certain people who would require glasses called anti-fatigue.

OBJECT OF THE INVENTION

In order to overcome the above-mentioned drawback of the state of the art, the present invention proposes a new method of diagnosing the state of ophthalmic fatigue of an individual, making it possible to determine precisely whether this individual requires glasses or not. anti-fatigue or special care (advice on the ergonomics of lighting, artificial tears to fight against dry eye, ...).

More particularly, according to the invention, there is provided a screening method as defined in the introduction, in which a step aO) of adjusting the size of the target and / or, prior to step a2) is provided. the position of the target relative to the individual, depending on the age of the individual. The Applicant has found that the measurement errors using a rule of the "RAF rule" type result from the gradual approximation of the target to the eyes of the individual, which allows the ciliary muscles to contract gradually until a threshold beyond which they are able to contract instantly.

The present invention is then no longer to progressively bring closer the target of the individual, but rather to adjust the position and / or the size of the target to a given value, then, once the target is set, to ask the individual to look at the target so that he can determine if he sees it clearly.

The size and / or position of the target is then predetermined according to the age of the individual, thanks to data from statistical studies that determine the minimum distance of accommodation that an individual is supposed to present. at a given age, if he does not suffer from any particular ophthalmic problem.

Some general points about ophthalmic fatigue are also mentioned here.

The minimum distance of accommodation of an individual evolves naturally with the age of an individual. This evolution does not constitute ophthalmic fatigue since it is durable and irreversible.

On the other hand, ophthalmic fatigue is a temporary and reversible state of fatigue of the ciliary muscles of the individual. It is a normal condition, which reaches healthy individuals after their ciliary muscles have been heavily stressed.

What the invention seeks here to determine does not concern then the irreversible component of the visual problems of the individual, but rather the occasional and non-pathological component of these problems.

During the implementation of the invention, it is not a question of comparing values measured on the individual with those of a healthy individual, but rather values measured on the individual whose ciliary muscles are tired with those that would be measured on the same individual, for example when waking up, when his ciliary muscles are rested.

Advantageously, if, in step a2), the target is seen blurred by the individual, it is provided following step a3) steps:

b1) enlargement of the target size and / or removal of the target relative to the individual of a predetermined value,

b2) the individual's assessment of the sharpness of the target, and

b3) if, in step b2), the individual sees the target more clearly, deducing a need for an anti-fatigue correction.

The correction of the size and / or the position of the target then makes it possible to check whether the lack of accommodation observed is due to an ophthalmic fatigue problem which a pair of anti-fatigue glasses can remedy, or if it is a more serious problem (in which case the individual will have to undergo further examinations).

Other advantageous and non-limiting characteristics of the process according to the invention are the following:

during step aO) only the distance between the target and the individual is set;

step b1) comprises inserting at least one correction lens between the eye of the individual and the target;

the correction lens has a non-zero spherical power and / or a non-zero cylindrical power and / or a non-zero prismatic power and / or an antireflection coating and / or a tinted coating, and / or is formed by a depth lens field;

in step aO), the distance between the target and the individual is also adjusted according to the time of the day at which the screening is carried out, and / or the geographical origin of the individual and / or the sharpness of the target and / or contrast of the target;

during step aO), only the target size is set;

step b1) consists in enlarging the size of the target;

prior to step a2), the individual is equipped with his usual correction equipment (for example his usual pair of spectacles or his usual contact lenses);

the steps a1) and a2) are carried out simultaneously or successively on the two eyes of the individual; and

- Following step a3), there is provided a step d) of storage and remote transmission, via a computer network, of the state of ophthalmic fatigue deduced in step a3).

The invention also proposes a screening device as defined in introduction, wherein said graduation reveals ages.

Other advantageous and non-limiting features of the device according to the invention are the following:

the support comprises means for positioning a correction lens, located between the support part and the target;

at least two graduations are provided showing age and provision is made for positioning means for a change of scale lens; and

- the target has at least one letter or one image.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings:

- Figure 1 is a schematic perspective view of a first embodiment of a screening device according to the invention;

FIG. 2 is a schematic perspective view of the target of the screening device of FIG. 1;

FIG. 3 is a schematic perspective view of a second embodiment of the screening device according to the invention;

FIG. 4 is a schematic perspective view of a third embodiment of the screening device according to the invention;

- Figure 5 is a schematic perspective view of a fourth embodiment of the screening device, adapted to implement a screening method according to the invention; and

FIG. 6 is a table illustrating the variations of the minimum distance of accommodation as a function of the age of the individuals and the power of the scaling lens.

In Figures 1, 3, 4 and 5, there are shown four embodiments of a screening device 100; 200; 300; 400 of a state of ophthalmic fatigue of an individual.

Ophthalmic fatigue (or "visual fatigue") is a reversible physiological effect resulting from excessive straining of the eye muscles and the retina, to try to maintain a clear image through inefficient adjustments. It is accompanied by a reduction in the capacity needed to perform a visual task and a modification of the strategy of accomplishing this task; it constitutes an alarm signal which should be treated.

Ophthalmic fatigue can result not only in subjective symptoms and physiological changes, but also in a decrease in visual performance.

Ophthalmic fatigue is more specifically studied in the document "Visual fatigue" issued by the department of environmental physiology of the INRS (National Institute of Research and Security) in March 1992.

In each of these four embodiments, the screening device 100; 200; 300; 400 is specifically intended to facilitate the task of an optician to determine whether or not a patient has a good near vision and if, therefore, it requires or not a pair of glasses said anti-fatigue.

For this, the screening device 100; 200; 300; 400 is intended to determine whether, given the age of the patient, each of the two eyes of the patient has a satisfactory "minimum distance of accommodation".

"Minimum distance of accommodation" means the minimum distance at which an individual can clearly see an object.

In the first three embodiments respectively shown in Figures 1, 3 and 4, the screening device 100; 200; 300 includes:

a support 1 10; 210; 310 having a bearing portion 1 1 1; 21 1; 31 1 to be applied against the face or glasses of the patient, and a slide 1 12; 212; 312

a target 120; 220; 320 slidably mounted on the slide 1 12; 212; 312 of the support 1 10; 210; 310, and

at least one graduation 130; 230, 231, 232; 330, 331 located along the slide 1 12; 212; 312 to locate the position of the target 120; 220; 320 on the slide 1 12; 212; 312.

According to a particularly advantageous characteristic of the screening device according to the invention, this graduation 130; 230, 231, 232; 330, 331 reveals ages.

According to an advantageous characteristic of this screening device, the support 1 10; 210; 310 further comprises positioning means 1 13; 213; 313 of a correction lens between the support portion 1 1 1; 21 1; 31 1 and the target 120; 220; 320, to facilitate the vision of the target, if necessary.

These positioning means 1 13; 213; 313 are therefore designed to receive a correction lens, if necessary, so that the latter remains removable.

They can therefore be in various forms, as long as they allow to position and extract the correction lens manually, without the aid of tools.

The different embodiments of the screening device will be more precisely described later in this presentation.

In Figure 1, there is shown the first embodiment of the screening device 100.

In this embodiment, the support 1 10 is in the form of a substantially cylindrical tube of revolution about a longitudinal axis A1.

This tubular support 1 10 here has a length of 30 centimeters, an internal diameter of 5 centimeters, and an outside diameter of 5.4 centimeters.

It is made in one piece by molding a transparent plastic material.

The bearing portion 11 January 1 of this tubular support 1 10, which is intended to be applied against the patient's face or against the pair of glasses that the patient wears, is then formed by one of the circular ends of this support tubular 1 10.

The slide 1 12 of this tubular support 1 10, in which the target 120 slides, is itself formed by a rectilinear longitudinal slot which extends over the entire length of the tubular support 1 10, parallel to the axis longitudinal A1, and which here has a width of 5 millimeters.

As shown in Figure 1, the graduation 130 on which appear ages is printed on a rectangular sticker, glued parallel to the slide 1 12, along it.

This sticker bears, in the manner of a ruler, two types of markings. It firstly, along its edge along the slide 1 12, twenty-three short dashes, parallel and spaced two by two, axes orthogonal to the longitudinal axis A1. It also bears, in front of at least part of these indents, figures indicating ages. Each dash is associated with a given age, between 18 and 40 years old. The spacing between the dashes increases from the bearing portion 11 1 to the opposite end of the tubular support 1 10.

Each of the ages noted on the graduation 130 indicates the age associated with the dash in front of which it is located. The ages noted on the graduation 130 increase from the bearing portion January 1 to the opposite end of the tubular support January 10.

Each dash is then located at a distance from the support portion 11 January 1 of the tubular support 1 10 which is substantially equal to the minimum distance of accommodation that an individual is expected to present at a given age (the one to which this dash is associated), if he does not suffer from any particular ophthalmic problem.

This distance could be obtained by a statistical study carried out on a representative sample of individuals not suffering from any particular ophthalmic problem.

Here, this distance denoted D _age is calculated by means of the following mathematical formula:

D _â ge = 1 / (A _age - G), with:

At _age the minimum distance of accommodation (expressed in diopters) expected for an individual of given age, and

G a correction coefficient.

The minimum amplitude of accommodation at _age (or "punctum proximum of accomodation"), expressed in diopters, is calculated according to the formula of Hofsetter, according to which:

The correction coefficient G is meanwhile chosen to be 0.

The result obtained is given, in millimeters, on the second column of the table of FIG.

This corrective coefficient G, which serves to modulate the threshold from which ophthalmic fatigue is estimated, could alternatively be chosen as non-zero, for example to take account of a lack of sharpness or a low contrast of the target 120.

It could also be chosen nonzero to take into account the geographical area in which the optician works. It has been found that the minimum distance of accommodation of an individual suffering no problem Ophthalmic particular varies from one geographical area to another.

The target 120, which is designed to slide along the slide 1 12, is more specifically shown in FIG. 2.

It has a reading portion 121, on which is represented any pattern, a gripping portion 122 easily manipulated by an optician to slide the target 120 along the slide 1 12, and a connecting portion 123 which connects the portion 121 to the gripping portion 122.

The reading portion 121 is housed inside the tubular support 1 10 and has a pattern easily recognizable by the patient.

This reading portion 121 is here in the form of a square plate, about 2 centimeters of sides, whose two main faces are oriented orthogonally to the longitudinal axis A1.

Its main face facing the support part 1 1 1 is the one on which the pattern is printed.

This pattern is here formed by a letter (here an "E"). It could alternatively be formed by a drawing such as an animal, or by a set of letters of varying sizes.

This pattern here has a black color and is drawn on a white background. Alternatively, it could be provided that the background is of a different color, for example green or red, and that the pattern has another color.

The gripping portion 122 is located outside the tubular support 1 10.

It is in the form of a rectangular wafer, which is here coplanar with the reading portion 121. Alternatively, it could be shifted relative to the reading portion 121, to ensure a better grip.

It carries here at one of its ends a point 124 which makes it possible to read precisely on the graduation 130 the age corresponding to the position of the target 120 along the slide 1 12.

The connecting portion 123 has a width equal, with the game, to the width of the slide 1 12 and a height equal, clearance, to the thickness of the tubular support 1 10, to guide the target 120 in translation along this slide 1 12.

As shown in FIG. 1, the positioning means, which make it possible to interpose a correction lens between the support part 1 1 1 of the tubular support 1 10 and the target 120, are here formed by a transverse slot 1 13.

This transverse slot 1 13 extends over half of the periphery of the tubular support 1 10, on either side of the slide 1 12. It allows to accommodate if necessary any correction lens, when the optician wish it. The use of this lens will be described below.

The detection of the possible state of ophthalmic fatigue of the patient by means of this screening device 100 is then operated in the following manner.

Beforehand, the optician questions the patient to know his age.

He also asks him to equip himself with his usual corrective equipment (for example, his glasses or his contact lenses).

The optician then adjusts the position of the target 120 in the slide 1 12 so that its point 124 is aimed at the graduation 130, the age indicated by the patient.

The optician then asks the patient to close one of his eyes, for example the left eye.

He then positions the screening device 100 in the axis of the patient's left eye, the support part 1 1 1 in contact with the patient's face or glasses, so that when the latter opens his left eye he can see the reading portion 121 of the target 120.

The optician then asks the patient to judge the sharpness of the letter printed on the target 120.

Depending on whether the patient succeeds or not, the optician deduces that the patient has or not a state of ophthalmic fatigue.

More precisely, if the patient judges the clear letter (for example if he can read the letter "E"), the optician deduces that the corresponding eye of the individual does not present a state of fatigue. The optician therefore deduces that the patient does not require, at least for his left eye, a pair of anti-fatigue glasses.

On the other hand, if the patient finds the letter tense (for example if he can not read the letter "E"), the optician carries out a complementary examination to check that only a state of fatigue affects the eye left of the wearer (and that this problem of vision is not more serious).

For this, the optician places a correction lens through the transverse slot 1 13 of the tubular support 1 10, whose power is such that it compensates for a slight lack of accommodation of the eye, artificially distancing and enlarging the size of the letter "E" seen by the patient.

The correction lens used will preferably be a simple convergent lens whose spherical power will be strictly positive (for example equal to 0.6 diopters). It may also be formed by a lens with depth of field.

Alternatively, it may be provided that this correction lens has a non-zero cylindrical power (alone or combined with a spherical power), to correct a possible cylindrical fatigue of the eye. We speak of sphero-cylindrical correction.

Whatever the type of this correction lens, we can also provide that it also has an antireflection coating (to increase the contrast of the letter "E" on the bottom) and / or a tinted coating (to change the color of the letter "E" and the background).

Anyway, once the correction lens engaged in the transverse slit 1 13, the optician asks the patient if he judges the letter sharper (for example if he manages to read the letter "E" represented on the target 120).

If it succeeds, the optician deduces that the patient requires a pair of anti-fatigue correction glasses.

On the contrary, if it does not succeed, the optician deduces that the patient suffers from ophthalmic problems other than simple fatigue, and therefore advises the patient to visit an optometrist.

The operations are then implemented in the same way, on the right eye of the patient.

According to a variant of this first embodiment, it would be possible to calculate three minimum distances of accommodation for each age, of which:

a normal distance of accommodation D ₂ = 1 / (18.5 - 1/3.

a maximum distance of accommodation Di = 1 / (15- 0.25.age),

a minimum distance of accommodation D ₃ = 1 / (24 - 0.4.age). We would thus obtain three scales of different graduations, offering the optician a certain freedom to choose the threshold from which he will estimate that there is ophthalmic fatigue.

In Figure 3, there is shown the second embodiment of the screening device 200. In this embodiment, the support 210 has a shape almost identical to that of the support 1 shown in FIG.

It thus has an end forming a bearing portion 21 1 to be pressed against the face or against the glasses of the patient, as well as a slide 212 in which the target 220 slides and a transverse slot 213 to accommodate a correction lens.

In this case, the support 210 is distinguished from the support 1 10 shown in Figure 1 by the only characteristics in which it has a reduced length and it comprises, parallel and in the vicinity of the transverse slot 213, between the bearing portion 21 1 and the target 220, a second transverse slot for accommodating a change of scale lens (whose function will be specified later in this presentation).

The target 220 has a shape identical to that of the target 120 shown in Figure 2.

In this embodiment, three graduations are also provided.

230, 231, 232 separate.

As shown in FIG. 3, each graduation 230, 231, 232 is carried by a rectangular sticker on which only ages are printed.

Each sticker is glued parallel to the slide 212, close to it and away from other stickers.

The ages printed on the stickers are not the same. Thus, regardless of its position on the slide 212, the target 220 points to three different ages, depending on whether this age is read on one or the other of the stickers.

It can thus be seen in FIG. 3 that one of the graduations 231 shows ages between 16 and 30 years, that another of the graduations 230 shows ages between 31 and 46 years, and that the last of the graduations 232 reveals ages between 37 and 49 years old.

The three graduations do not have the same scale. To go from one graduation to another, a change of scale lens is then used, which is placed for this purpose in said second transverse slot, between the patient's eye and the target.

The use of three graduations thus makes it possible to reduce the length of the tubular support 210, in that to make it appear on one and the same graduation ages between 18 and 49 years, it would be necessary to provide a support of a length of about 50 centimeters.

The use of three graduations also makes it possible to improve the accuracy of the measurements. By comparing FIGS. 1 and 3, it can be seen that the ages 18 and 19 are spaced more apart on the graduation 231 of FIG. 3 than on the graduation 130 of FIG. 1, which facilitates the precise placement of the target 220 in front of the desired age.

On the first marking 230, each printed age is located at a distance from the support portion 21 1 of the tubular support 210 which is substantially equal to the minimum distance of accommodation that an individual is expected to exhibit at a given age s' he does not suffer from any particular ophthalmic problem. This distance denoted D _age is calculated by means of the aforementioned mathematical formula and is provided, in millimeters, on the second column of the table of FIG. 6.

On the second and third markings 231, 232, each printed age is located at a distance from the support portion 21 1 of the tubular support 210 which is substantially equal to the minimum distance of accommodation that an individual is supposed to present to a given age, if he does not suffer from any particular ophthalmic problem and if he wears a pair of glasses equipped with lenses whose spherical powers are either -5 diopters (graduation 231) or 1, 5 diopters (graduation 232 ).

The distances calculated according to the age of the patient are respectively provided, in millimeters, on the fourth and third columns of the table of FIG.

It is understood that when no scaling lens is engaged in the second transverse slot 214, the graduation to be used by the optician to place the target 220 is the graduation 230 (in front of which appears the inscription "+ 0δ"). When a -5 dioptres scaling lens is engaged in the second transverse slot 214, the graduation to be used by the optician to place the target 220 is the graduation 231 (in front of which appears the inscription " -5δ "). When a +1.5 diopter scaling lens is engaged in the second transverse slot 214, the graduation to be used by the optician to place the target 220 is the graduation 232 (in front of which appears the inscription "+1 .5δ"). The detection of the possible state of ophthalmic fatigue of the patient by means of this screening device 200 is then operated in substantially the same manner as with the screening device 100 shown in FIG.

The only difference is that:

if the patient is between the ages of 31 and 46, the optician must adjust the position of the target 220 using the graduation 230;

if the patient is between 18 and 31 years old, the optician must engage in the second transverse slot 214 a scaling lens of -5 diopters and must adjust the position of the target 220 using the graduation 231; and

if the patient is between 47 and 49 years old, the optician must engage in the second transverse slot 214 a scaling lens of +1.5 diopters and must adjust the position of the target 220 using the graduation 232.

In FIG. 4, the third embodiment of the screening device 300 is shown.

In this embodiment, the principle used to detect a possible state of ophthalmic fatigue of the patient is the same as that used with the screening device 200 of FIG. 3.

The screening device 300 is on the other hand binocular, and thus makes it possible to detect a possible state of fatigue of the patient at choice simultaneously or successively on the two eyes of the patient.

In this embodiment, the carrier 310 is generally in the form of a pair of binoculars. It more precisely has a generally parallelepipedal shape elongate along a longitudinal axis A3, with two upper faces 310A and lower, two side faces 310B, and two end faces called front face 310C and rear face.

The front face 310C of this support 310 is substantially flat. It has a width of about 18 centimeters and a height of about 7 centimeters. It is opened by two rectangular windows 315 allowing the patient to look with his two eyes inside the support 310. These windows 315 are here closed by transparent windows, to prevent the infiltration of dust inside the support 310 .

To allow the patient to see the target 320, there is provided inside the support 310 lighting means, here formed by light-emitting diodes powered by electric batteries. The bearing portion 31 1 of this support 310, which is intended to be applied against the face or against the glasses of the patient, is then formed by the front face 31 OC of this support 310. It is in particular provided a hollow recess in the lower edge of the front face 31 OC, which forms a nose rest.

The slideway 312 of this support 310, in which the target 320 slides, is itself formed by a rectilinear longitudinal slot which extends over only a portion of the length of the upper face 310A of the support 310, parallel to the axis longitudinal A3. Here, this slide 312 does not open on the front face 310C or on the rear face of the support 310.

The target 320 is identical to that shown in Figure 2. It is positioned in the support 310 so that it is simultaneously visible by the two eyes of the patient through the windows 315.

In this embodiment, there are two distinct graduations 330, 331, arranged on either side of the slideway 312.

Each graduation 330, 331 is carried by a rectangular sticker on which are printed ages. These two stickers are then glued parallel to the slideway 212, along the latter.

As in the second embodiment of the screening device shown in FIG. 3, the ages printed on the two stickers are not represented on the same scale.

We observe in Figure 4 that one of the graduations 330 shows ages between 28 and 46 years, while the other graduations 331 shows ages between 16 and 27 years.

It is then provided inside the support 310 two scaling lenses (not visible in the figures), adapted to be engaged in front of the two windows 315 of the support 310 or to be released therefrom, for allow to use one or other of the two graduations 330, 331.

The screening device 300 then comprises means for manual operation of these two scaling lenses, for engaging or disengaging the windows 315 of the support 310, independently of one another.

Here, these maneuvering means are formed by two sliders 314 which are located on the upper face 310A of the support 310, opposite the two windows 315, and which are movable between two positions in which they point to either one of two numbers marked "1" and "2".

It is then understood that when the sliders 314 are placed on the number "1", the graduation to be used by the optician to position the target 320 is the graduation 330 (in front of which appears the inscription "1"), and that when the cursors 314 are placed on the number "2", the graduation to be used by the optician to position the target 320 is the graduation 331 (in front of which appears the inscription "2").

It is furthermore provided inside the support 310 two masks (not visible in the figures), to hide one or the other of the windows 315 when the optician wishes to use the screening device 300 successively on each eye of the patient and not simultaneously on both eyes of the patient.

The screening device 300 then comprises means for manual operation of these two masks, for engaging or disengaging the windows 315 of the support 310, independently of one another.

Here, these maneuvering means are formed by two sliders 316 which are respectively located on the two lateral faces 310B of the support 310, at the height of the two windows 315, and which are movable between two positions in which they point to a black circle or to a black disk.

It will be understood that when the cursors 316 are placed on the black disks, the windows 315 are closed, and when the cursors 316 are placed on the black circles, the windows 315 are unobstructed to leave the target 320 visible through the windows 315. .

It is also provided inside the support 310 two 0.6 diopter correction lenses (not visible in the figures) adapted to be engaged in front of the two windows 315 of the support 310 or to be released therefrom.

The screening device 300 then comprises means for manual operation of these two correction lenses, making it possible to engage or disengage them from the windows 315 of the support 310, independently of one another.

Here, these maneuvering means are formed by two sliders 313 which are located on the upper face 310A of the support 310, facing the two windows 315, and which are movable between two positions in which they point towards one or the other two acronyms marked "0" and "O".

It will be understood that when the cursors 313 are placed on the symbol "0", the correction lenses are not situated in the axis of the windows 315, while when the sliders 313 are placed on the symbol "O", the correction lenses are located in the axis of the windows 315.

The method of use of this screening device 300 is the same as that described above, with the difference that it is then possible to perform this screening choice, simultaneously or successively on both eyes of the patient.

In case of simultaneous binocular screening on the two eyes of the patient, it can be provided that the correction lenses each have a non-zero prismatic power, to correct any prismatic fatigue of the eyes.

In FIG. 3, the fourth embodiment of the screening device 400 is shown.

In this embodiment, the screening device is formed by a simple computer tablet which comprises a frame 402, a touch screen 401 engaged in the frame 402, detection means 410 of the distance separating the touch screen 402 from the face of the patient, and a central unit that is housed in the chassis 402 and in which is stored diagnostic software.

The detection means 410, which could for example be formed by a single camera, are here formed by an ultrasonic distance sensor.

The detection of the possible state of ophthalmic fatigue of the patient by means of this tablet 400 is then operated in the following manner.

Beforehand, the patient starts the diagnostic software and enters its age. He also equips his glasses if he usually wears. He then spreads the tablet 400 from his face to hold it at arm's length.

With the detection means 410, the diagnostic software then acquires the distance separating the touch screen 401 from the patient's eyes.

The software then controls the display on the touch screen 401 of a message telling the patient to move the touch screen 401 closer or further away from his eyes. The objective of this operation is that the distance separating the touch screen 401 from the patient's eyes is equal to the distance D _age (as defined in the first embodiment of the invention).

The software then controls the display on the touch screen 401 of the letter "E", as well as a message and two buttons to allow the patient to enter the result of this examination, so that the software acquires the information whether or not the patient was able to read the letter displayed. If successful, the software controls the display on the touch screen 401 of a message indicating to the patient that it does not require a pair of anti-fatigue glasses.

On the contrary, if it has not been successful, the display on the touch screen 401 of a message telling the patient to move the touch screen 401 away from his eyes. When the touch screen 401 is sufficiently far apart, the software controls the display on the touch screen 401 of an enlarged letter "E" 420 in order to verify that only a state of fatigue affects the eyes of the wearer (and that this problem vision is not more serious).

The size of this letter "E" is calculated in relation to the size of the letter

"E" initially displayed such that the letter "E" appears to constant size for the patient even as the touch screen 401 has been moved back. A calculation method allowing the letter "E" to appear to the patient with an angular size found is presented in US7393102.

Holding the tablet 400 again at arm's length, the patient then tries to read the letter "E" displayed on the touch screen 401.

The software then controls the display on the touch screen 401 of a message and two buttons, to enable the patient to enter the result of this examination on the tablet 400, so that the software acquires the information that the patient was able to read the letter displayed on the screen.

If successful, the software controls the display on the touch screen 401 of a message indicating to the patient that it requires a pair of anti-fatigue glasses.

On the contrary, if it has not been successful, the software controls the display on the touch screen 401 of a message telling the patient to go to an optometrist for further examinations.

The diagnostic software of the tablet 400, if the latter is connected to a computer network, can then order the sending of a message to an optician providing the result of the measurement made.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

In particular one could expect that the size of the letter "E" displayed evening adjusted also according to the time of the day to which is carried out the screening, the eyes of the patient being naturally more tired at night than the morning.

Alternatively, one could provide a screening device such as that shown in the first embodiment, but without a transverse slot for receiving a correction lens. So, when the patient fails to read the letter "E" printed on the target, the optician could, not use a correction lens, but rather move the target back a distance to facilitate the reading of the letter "E", this distance corresponding for example to two years on the graduation.

It could also be provided that the support portion of the screening device is adapted to rest on the patient's face, away from his eyes. Thus, the screening device will rest in the same way on the patient's face, that is to say in the same position, whether or not the patient wears a pair of glasses.

According to another variant of the invention not shown in the figures, it could be provided that the correction lens is mounted on the support via a pivot, so as to be retractable. It would thus be mobile between a position of use in which it would be between the support part and the target, and a retracted position in which it would be angularly offset by 90 degrees from its position of use.

Claims

1. Method for detecting an ophthalmic fatigue state of an individual, comprising steps:

a1) for positioning a target (120; 220; 320; 420) relative to the individual such that the target (120; 220; 320; 420) is visible to at least one of the two eyes of the individual; ,

a2) judgment by the individual of the sharpness of the target (120; 220; 320;

420), and

a3) of deducing a state of ophthalmic fatigue of the individual according to whether the target (120; 220; 320; 420) is seen by the individual in a clear or fuzzy manner, characterized in that it comprises, prior to step a2), a step aO) of adjusting the size of the target (120; 220; 320; 420) and / or the position of the target (120; 220; 320; 420) relative to the individual; , depending on the age of the individual.

2. Screening method according to the preceding claim, wherein if, in step a2), the target (120; 220; 320; 420) is blurred by the individual, it is provided after step a3) steps :

b1) enlarging the size of the target (120; 220; 320; 420) and / or moving away from the target (120; 220; 320; 420) relative to the individual by a predetermined value;

b2) judgment by the individual of the sharpness of the target (120; 220; 320;

420), and

b3) if, in step b2), the individual sees the target (120; 220; 320; 420) more clearly than in step a2), deriving a need for an anti-fatigue correction .

3. Screening method according to one of claims 1 and 2, wherein during step aO), only the distance between the target (120; 220; 320; 420) and the individual is set.

4. Screening method according to claims 2 and 3, wherein step b1) comprises inserting at least one correction lens between the eye of the individual and the target (120; 220; 320; 420).

5. Screening method according to the preceding claim, wherein the correction lens has a non-zero spherical power and / or a non-zero cylindrical power and / or a non-zero prismatic power and / or an antireflection coating and / or a tinted coating, and / or is formed by a depth-of-field lens.

6. Screening method according to one of claims 1 and 2, wherein during step aO), only the size of the target (120; 220; 320; 420) is set.

7. Screening method according to claims 2 and 6, wherein step b1) is to enlarge the size of the target (120; 220; 320; 420).

8. Screening method according to one of the preceding claims, wherein, in step aO), adjusting the size of the target (120; 220; 320; 420) and / or the position of the target ( 120; 220; 320; 420) in relation to the individual is also based on the time of day to be screened, and / or the geographic origin of the individual and / or the sharpness of the target (120; 220; 320; 420) and / or the contrast of the target (120; 220; 320; 420).

9. Screening method according to one of the preceding claims, wherein, prior to step a2), equip the individual of his usual correction equipment.

10. Screening method according to one of the preceding claims, wherein the steps a1) and a2) are performed simultaneously or successively on both eyes of the individual.

1 1. Screening method according to one of the preceding claims, wherein, after step a3), there is provided a step c1) remote storage and transmission, via a computer network, the state of ophthalmic fatigue deduced in step a3).

12. A device (100; 200; 300) for detecting an ophthalmic fatigue state of an individual, comprising:

- a support (1 10; 210; 310) having a bearing portion (1 1 1; 21 1; 31 1) to be applied against the face or against the glasses of an individual and a slide (1 12; 212; 312)

a target (120; 220; 320) slidably mounted on the slide (112; 212; 312) of the support (110; 210; 310), and

at least one graduation (130; 230, 231, 232; 330, 331) along the slide (112; 212; 312) for locating the position of the target (120; 220; 320) on the slide ( 12, 212, 312), characterized in that said graduation (130; 230,231,232; 330,331) discloses ages and that the support (1,10; 210; 310) includes positioning means (1,13; 213; 313); located between the support portion (1 1 1; 21 1; 31 1) and the target (120; 220; 320), which are adapted to accommodate any correction lens as needed to facilitate the vision of the target.

13. Screening device (200; 300) according to claim 12, wherein at least two graduations (230, 231, 232; 330, 331) are provided, showing ages and in which positioning means are provided ( 214; 314) of a scaling lens, located between the bearing portion (21 1; 31 1) and the target (220; 320).

14. Screening device (100; 200; 300) according to one of claims 12 to 13, wherein the target (120; 220; 320) has at least one letter or one image.